New progress in Bioinspired Uni-directional Liquid Spreading Surface from the Peristome of Nepenthes alata

Time: 2017-03-10 00:43 Click:788

Uni-directional liquid spreading without energy input has gained much attention due to their potential applications such as microfluidic device and energy field. For the past years, various liquid directional transport strategies have been discovered from nature, such as spider silk and cactus spine with 1D conical spine structure, and desert beetle with patterned wettability.

Figure 1 Bioinspired uni-directional liquid spreading surface

Prof. Huawei Chen, Prof. Deyuan Zhang from Beihang University and Prof. Lei Jiang from Chinese Academy of Sciences have firstly discovered uni-directional liquid spreading on the peristome of N.alata. (Nature2016, 532, 85-89.)The structural characterization demonstrated that the uni-directional liquid spreading mainly results from its unique structural features, i.e., a sharp edge with an arch-shaped outline aligning at the bottom of the microgroove, which increases the difficulty of bionic fabrication. Recently, Prof. Chen’s team extracted feature structures of the peristome surface for creative design, and finally developed two-step UV inclined photolithography to fabricate bioinspired uni-directional liquid spreading surface (Figure 1). This study was published on Journal Small in Special Issue: Superwettability, and chosen as cover article.(Small 2017, 13, 1601676.)

Figure 2 The influence of structure features to liquid spreading

Various types of bioinspired surface were fabricated by tuning the feature structures, i.e., the shape of pit outline and pit inclined angle. Their effects on anisotropic liquid spreading were compared, and uni-directional liquid spreading was achieved with arc pit outline and inclined pitsimultaneously (Figure 2). The underlying mechanism has been further expanded by analyzing liquid spreading ability in front direction based on Taylor capillary rise effect and liquid pinning ability in rear direction through edge pinning effect.

This bioinspired uni-directional liquid spreading surface with long spreading distance and fast spreading speed properties can be applied on various fields such as microfluidic devices, non-powered deliver systems and self-lubrication in mechanical engineering.